Drawing-board attachment.



E. S. GOODSPEED.

DRAWING BOARD ATTACHMENT.

APPLICATION FILED SEPT, 29. um.

1,288,871. Patented Dec. 24, 1918.

WITNESSES INVENTOR FiGoOdgoegd, flmflw 6 24 4;

ELVIN S. GOODSPEED, OF WILKINSBURG, PENNSYLVANIA.

DRAWING-BOARD ATTACHMENT.

Specification of Letters Patent.

Patented Dec. 24, 1918.

Application filed September 29, 1917. Serial No. 194,050.

To all whom it may concern:

Be it known that I, ELVIN S. Goonsrnnl), a citizen of the United States, residing at Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Drawing- Board Attachments, of which the following is a specification.

This invention relates to an attachment for a drawing board and has for its primary object to provide a device of this character by means of which parallel movements of a straight edge across the board will be assured and an accidental displacement thereof prevented.

An object of the invention is the method of moving the straight edge so that the same may have a step by step movement for obvious reasons.

Besides the above my invention is distinguished in the use of a measuring device by means of which the travel of the straight edge can be measured.

With these and other objects in view the invention will be better understood from the following detailed description taken in connection with the accompanying drawing wherein Figure 1 is a fragmentary view of a drawing board with my invention applied thereto.

Fig. 2 isa sectional view.

Fig. 3 is a side elevation.

Each end of the drawing board has secured thereto in any suitable manner such as by the screws 1 a rack bar 2 with which cooperates gears 3 fixed upon a shaft 4.

This shaft is rotatably supported by one member 5 of each of a plurality of hinges 6 the other member 7 of which is secured to a straight edge 8 arranged in engagement with the surface of the board. From this arrangement it will be seen that the gears may be readily swung out of engagement with the rack bar for obvious reasons and when the gears are in engagement with the rack bar the straight edge 8 is restricted in its movement thus assuring the absolute parallel movement thereof over the drawing board.

Another feature of my invention is the cooperation between the teeth of the rack bar and the teeth of the gears may be relied on to properly space the straight edge in each movement thereof.

If found advisable in practice the member 6 of the end hinges may be stamped to form a guard 9 extending over the gear. Cooperating with one of the gears as clearly shown in Fig. 2 is a measuring device 10 consisting of a scaled knob 11 the scales of which being arranged so as to cooperate with the pointer 11 on the guard 9 that is associated therewith. This knob 11 is loose upon the shaft and depends for its movement by the frictional engagement between it and the gear 3 brought about by the spring 13 bearing upon the knob at one end with the other end bearing against a collar 14 mounted upon the shaft 4:.

By this arrangement in a simple manner I am able to determine the distance of travel of the straight edge as under normal conditions the knob 12 moves with the gear 3.

For the purpose of reducing mental efiort upon the part of the operator the knob 11 is mounted as illustrated so that at the beginning of a measurement the numeral 1 may be brought opposite the pointer 11 by simply holding the parallel square against movement while rotating the knob 11 upon the shaft.

It is to be understood that the structural embodiment of the invention as a whole and its various features as shown is merely illustrative and not restrictive, since I am well aware that many of the details of construction can be widely varied without departing from the spirit of the invention. I therefore do not desire to be limited in these particulars or in any others, except as set forth in the appended claims.

Having described my invention what I claim is;

1. In combination a drawing board, a rack bar secured to each end of the board, a straight edge, a gear hinged to each end of the straight edge and engaging rack bar and a measuring device cooperating with a gear for the purpose set forth.

2. In combination, a drawing board, a rack bar connected to each end of the board, a straight edge and gears hinged tothe straight edge and engaging the rack bar.

3. In combination, a drawing board, a rack bar connected to the drawing board, a straight edge, a gear cooperating with the rack bar, a hinge supporting the gear upon the straight edge, a scaled knob mounted for rotation relative to the gear and yieldable means for holding the knob in frictional engagernent With the gear.

4:. In combination, a drawing board, a rack bar connected to the drawing board, a straight edge, a gear cooperating With the rack bar, a hinge supporting the gear upon the straight edge, a scaled knob mounted for rotation relative to the gear and a spring holding the knob in frictional engagement 10 with the gear.

In testimony whereof I afiix my signature.

ELVIN S. GOODSPEED.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, I). 0. r 

